The present invention pertains to improvements in the field of offset lithography. More particularly, the invention is concerned with an apparatus for generating proofs of print signatures.
The process of offset printing from digitally generated information requires many steps that result in composite images and text on film. This film is used to make offset printing plates. The plates are then mounted on a printing press to produce multiple impressions on paper. Prior to committing the result of such a complex process to the press, that is to commence printing thousands of impressions, it is necessary to make one impression as a proof for obtaining approval of the customer prior to printing.
Printers print multiple page images on both sides of a large sheet of paper. Such a printed sheet is called a print signature. A single printed side, on the other hand, is called a flat. Thus, a print signature is composed of two flats printed on opposite sides of a sheet. The page images on each flat are positioned in a manner such that they are in the correct sequence after folding the print signature. The proof that a printer requires must have is the proof of the print signature.
Proofs of print signatures are prepared from the films, and if corrections have to be made, new films incorporating the necessary corrections have to be generated again. This results in extra manpower and cost of generating new films and new proofs for each and every iteration.
Technology has made it possible to generate offset printing plates directly without the intermediate steps of generating a film and then the plate from the film. This makes it impossible to generate proofs prior to printing. As most printers are unwilling to print without obtaining the approval of a proof by their customer, they are unable to use such a new technology.